I've been all set to buy a HX-620 for my new i7 system for a while now but all these squealing/buzzing/whining stories have really put me off, though I never seem to see it mentioned in reviews. Factored a lot into my mobo/gfx choice as well. Example here if you don't know what I'm talking about: http://www.youtube.com/watch?v=C4d23F2jehQ

Problem is after extensive reading around, Seasonics really seem to be prone to this issue, and of course they supply most other majors like Corsair and Antec (though not every model). So has anyone heard of the squealing phenomenon happening with the Modu82+ 625W? Very impressed with its review. Or any other PSU I should look at?

I'm extremely happy with my Modu82+ 625W... but I've also read some less flattering reports on it. Some people have reported that their fan made a ticking noise almost as soon as they turned it on. No such problems with mine.

Sadly, variations between individual units seem very common in the field of power supplies. Even if you opt for one with 99% good reviews, you might get a lemon and need to RMA it.

The GPU/PSU interactions have been going on for quite a while. Many video cards seem to throw a lot of signal garbage back into the PSU (and anything else connected in the system). Due party to poorly engineered VRMs in the video cards. It's not only the PSU that gets affected; I think noise in the audio card line is also caused partly by bad video card circuitry. My guess is that if you powered the video card off a different PSU altogether, the system PSU would not make this squealing sound. Of course, this is impossible, as the video card plugs into the motherboard, and that slot is powered by the PSU.

One possible solution, not to be messed with at home, appears to be small caps across the DC output terminals -- just something I heard.

I'm extremely happy with my Modu82+ 625W... but I've also read some less flattering reports on it. Some people have reported that their fan made a ticking noise almost as soon as they turned it on. No such problems with mine.

I just read that too, worried me a bit, and there's one report of squealing on the Modu82+ 425W on newegg, none on the 625. I'm having trouble finding where I'd have to send an Enermax to for RMA because I'm in Australia, does anyone know?

And yeah I know this problem seems to crop up totally randomly between gfx/mobo/psu interaction, I got the feeling Gigabyte's i7 boards had this more than the Asus ones, so I'm going to get a P6T, and for graphics I know recent nVidia cards are very squeal-happy so I'm buying a Galaxy 275 OC that's been marketed as having digital PWM. I guess all I can do is choose parts that will minimise my chances of squealing happening.

edit: I think I've decided to buy an Antec CP-850. I know 850 is overkill, but it's so cheap, and reviews are excellent and say it's near silent. Plus the technology is so new/different I like my chances with it better.

The GPU/PSU interactions have been going on for quite a while. Many video cards seem to throw a lot of signal garbage back into the PSU (and anything else connected in the system). Due party to poorly engineered VRMs in the video cards. Only option here other than being an electrical engineer and making your own (good)VRM system and interfacing it with the card, is to get a good company to make your card. Like high quality names like Asus as compared to some no name crap card or something. It's not only the PSU that gets affected; I think noise in the audio card line is also caused partly by bad video card circuitry. My guess is that if you powered the video card off a different PSU altogether, the system PSU would not make this squealing sound. Sounds like a decent plan, and you COULD power the card entirely off of another PSU, you would have to do a lot of soldering and trace cutting (cutting the power traces that go from the graphics card to the motherboard and soldering wires there to power those traces from another PSU) but I think just powering the card from another PSU's 6 pin power supply would be worth a try.Of course, this is impossible, as the video card plugs into the motherboard, and that slot is powered by the PSU.

One possible solution, not to be messed with at home, appears to be small caps across the DC output terminals -- just something I heard. Yes, sounds logical, but I would be willing to bet that PSUs already have some filter or decoupling capacitors across the DC output. Now the capacity/quality of these caps maybe could be modified, I doubt that would succeed in anything though.

One thing that I would think of would be to connect the ground pin on your wall outlet to the ground on the PSU's DC rails. Let me explain. AC is basically DC, but the + and - switch 60 times a second. So one wire will be + and the other be -, and then will flip, so the first is - and the second is +. Typical household AC does this 60 times a second. (60hz ever heard of it?) (AC is used because it is easier to transport over distances and in great quantities, if DC was used in house wiring the + wire would have to be really thick because of the current going across it and the heat generated, AC splits the heat and current going across into 2 lines) so your power supply (using a bridge rectifier, 4 diodes in it's simpilest form) converts the AC to DC (it doesn't really convert so to say, it more or less splits up the + and - into 2 constant streams instead of them switching back and forth)

But on most power outlets you have the little hole under the 2 prong slots, this is (I think) true earth ground. What someone could try would be running a wire from that earth ground hole, and connecting it to the GND on all of the DC rails for the PC. This would effectively provide a "true" ground to the system instead of the "artificial" ground generated by the bridge rectifier.

Here's the 1 issue with my theory. I wouldn't be surprised if the PSUs already connect the true earth ground to the DC output's ground...if they do my theory is pointless because it's already being accomplished.

MikeC, where does the graphics card throw out signal garbage? It would have to throw it out to the GND line right? It can't throw out signal garbage on the + power lines can it? Or does it throw the signal trash out over the PCI bus? I heard that PCI Express is electrically isolated so that (I assume) if a video card put out signal garbage it would be isolated from the rest of the system...right?

Well, my new system's been going for almost a week now, and... IT SQUEALS. Nowhere near as bad as some people have it like in that youtube video, but still. When I put my head near the case I can hear it squealing all the time, not loud enough to notice at my desk but it randomly gets louder in games, I can't tell exactly which part it's coming from. I spent so much time picking parts that would minimise my chances of getting squeals so I'm pretty pissed off. An AU$2.2k machine shouldn't do this.

Asus P6T
i7 920
Antec CP-850
Galaxy GTX275 OC (marketed as having digital PWM, a lot of good that did me)

I'm extremely happy with my Modu82+ 625W... but I've also read some less flattering reports on it. Some people have reported that their fan made a ticking noise almost as soon as they turned it on. No such problems with mine.

Sadly, variations between individual units seem very common in the field of power supplies. Even if you opt for one with 99% good reviews, you might get a lemon and need to RMA it.

Was extremely happy with my Modu82+ 625W as well. But after only 4 months of use I have a loud ticking noise from the fan that starts about 30 minutes after turning on and is getting worse every day. Time to see how customer friendly the Enermax warranty policy is.

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